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  1. IMPALA
  2. IMPALA-3902 Multi-threaded query execution
  3. IMPALA-9015

Use better algorithm for allocating scan ranges to finstances within a daemon in schedule

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    Details

    • Type: Sub-task
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: Impala 3.4.0
    • Component/s: Distributed Exec
    • Labels:
      None
    • Epic Color:
      ghx-label-9

      Description

      Currently the scheduler uses a single-pass algorithm to allocate scan ranges to nodes. It has several deficiencies:

      • It doesn't guarantee that the desired number of instances are created. E.g. if mt_dop is 4, there are 3 impalads and 9 scan ranges, it should create 3 instances per impala but doesn't reliably.
      • It tends to over-allocate to the first instances it visits.
      • The result depends quite a bit on the input order of the scan ranges.

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            • Assignee:
              tarmstrong Tim Armstrong
              Reporter:
              tarmstrong Tim Armstrong
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              • Created:
                Updated:
                Resolved: